Im-18 crystalline solid and process for its preparation

ABSTRACT

The invention concerns a crystalline solid designated IM-18 which has the X-ray diffraction diagram given below. Said solid has a chemical composition expressed by the empirical formula: mXO 2 :nGeO 2 :pZ 2 O 3 :qR:sF:wH 2 O, in which R represents one or more organic species, X represents one or more tetravalent element(s) other than germanium, Z represents at least one trivalent element and F is fluorine.

TECHNICAL FIELD

The present invention relates to a novel crystalline solid hereinaftertermed IM-18, having a novel crystalline structure, and to a process forpreparing said solid.

PRIOR ART

During the past few years, the search for novel molecular sieves has ledto the synthesis of a wide variety of this class of products. A widevariety of aluminosilicates with a zeolitic structure characterized inparticular by their chemical composition, the diameter of the pores theycontain, the shape and geometry of their microporous system has thusbeen developed.

Of the zeolites synthesized over the last forty years, a certain numberof solids have allowed significant progress to be made in the fields ofadsorption and catalysis. Examples of these which may be cited are Yzeolite (U.S. Pat. No. 3,130,007) and ZSM-5 zeolite (U.S. Pat. No.3,702,886). The number of novel molecular sieves, including zeolites,synthesized each year is constantly increasing. A more completedescription of the various molecular sieves which have been discoveredcan be obtained by referring to the following work: “Atlas of ZeoliteFramework Types”, Ch Baerlocher, WM Meier and DH Olson, Fifth RevisedEdition, 2001, Elsevier. The following may be cited: NU-87 zeolite (U.S.Pat. No. 5,178,748), MCM-22 zeolite (U.S. Pat. No. 4,954,325) orgallophosphate (cloverite) with structure type CLO (U.S. Pat. No.5,420,279) or the following zeolites: ITQ-12 (U.S. Pat. No. 6,471,939),ITQ-13 (U.S. Pat. No. 6,471,941), CIT-5 (U.S. Pat. No. 6,043,179),ITQ-21 (WO-02/092511), ITQ-22 (Corma A et al, Nature Materials 2003, 2,493), SSZ-53 (Burton A et al, Chemistry: A Eur. Journal 2003, 9, 5737),SSZ-59 (Burton A et al, Chemistry: A Eur. Journal 2003, 9, 5737), SSZ-58(Burton A et al, J Am Chem Soc 2003, 125, 1633) and UZM-5 (Blackwell, CS et al, Angew Chem, Int Ed, 2003, 42, 1737).

Several of the zeolites cited above have been synthesized in a fluoridemedium, in which the mobilizing agent is not the usual hydroxide ion butthe fluoride ion, using a process initially described by Flanigen et al(U.S. Pat. No. 4,073,865) then developed by J-L Guth et al (Proc IntZeol Conf Tokyo 1986, p 121). The pHs of the synthesis media aretypically close to neutrality. One of the advantages of such fluorinatedreaction systems is that it allows purely silicic zeolites containingfewer defects to be obtained than the zeolites obtained in thetraditional OH medium (JM Chézeau et al, Zeolites, 1991, 11, 598).Another decisive advantage linked to the use of fluorinated reactionmedia is that novel topologies for the silicic framework containingdouble rings with four tetrahedra (D4R) can be obtained, as is the casefor ITQ-7, ITQ-12 and ITQ-13 zeolites. Further, the joint use of sourcesof germanium and silicon in the synthesis media may also allow novelframeworks of that type to be produced, i.e. containing D4R units, bothin a conventional non-fluorinated basic medium and in a fluorinatedmedium, as is the case for ITQ-17 and ITQ-21 zeolites (A Corma et al,Chem Commun 2001, 16, 1486, Chem Commun 2003, 9, 1050) or IM-12 (J-LPaillaud et al, Science, 2004, 304, 990).

DESCRIPTION OF THE INVENTION

The present invention concerns a novel crystalline solid, termed anIM-18 crystalline solid, having a novel crystalline structure. Saidsolid has a chemical composition expressed by the following generalformula: mXO₂:nGeO₂:pZ₂O₃:qR:sF:wH₂O, in which R represents one or moreorganic species, X represents one or more tetravalent element(s) otherthan germanium, Z represents at least one trivalent element and F isfluorine, m, n, p, q, s and w respectively representing the number ofmoles of XO₂, GeO₂, Z₂O₃, R, F and H₂O and m is in the range 0.5 to 0.9,n is in the range 0.1 to 0.5, p is in the range 0 to 0.1, q is in therange 0 to 0.2, s is in the range 0 to 0.2 and w is in the range 0 to 1.

In its as-synthesized form, the IM-18 crystalline solid of the inventionhas an X-ray diffraction diagram which includes at least the peaks setout in Table 1. In its calcined form, the IM-18 crystalline solid of theinvention has an X-ray diffraction diagram which includes at least thepeaks set out in Table 2. This novel IM-18 crystalline solid has a novelcrystalline structure.

These diffraction diagrams are obtained by radiocrystallographicanalysis using a diffractometer employing the conventional powdertechnique with the K_(α1) peak of copper (λ=1.5406 Å). From the positionof the diffraction peaks represented by the angle 2θ, the characteristicinterplanar spacings d_(hkl) of the sample are calculated using theBragg relationship. The error estimation Δ(d_(hkl)) in the measurementof d_(hkl) is calculated by the Bragg relationship as a function of theabsolute error Δ(2θ) in the measurement of 2θ. An absolute error Δ(2θ)of ±0.02° is normally acceptable. The relative intensity I/I₀ in eachvalue of d_(hkl) is measured from the height of the correspondingdiffraction peak. The X-ray diffraction diagram of the IM-18 crystallinesolid of the invention in its as-synthesized form comprises at least thepeaks at values of d_(hkl) given in Table 1. The X-ray diffractiondiagram of the IM-18 crystalline solid of the invention in its calcinedform comprises at least the peaks at values of d_(hkl) given in Table 2.In the d_(hkl) column, the mean values of the interplanar spacings areindicated in Angstroms (Å). Each of these values must be supplemented byan error measurement Δ(d_(hkl)) of between ±0.2 Å and ±0.001 Å.

TABLE 1 Mean values of d_(hkl) and relative intensities measured on anX-ray diffraction digram of the as-synthesized IM-18 crystalline solid 2theta (°) d_(hkl) (Å) I/I₀ 7.87 11.33 Mw 8.74 10.11 Vw 10.39 8.50 W15.77 5.62 Vs 17.61 5.03 W 18.52 4.79 Vw 20.86 4.26 W 21.25 4.18 Vw23.01 3.86 W 23.76 3.74 Mw 24.04 3.70 W 25.98 3.43 Mw 26.81 3.32 Mw29.72 3.00 Vw 30.28 2.95 Vw 31.81 2.81 W 33.46 2.68 W 36.03 2.49 Vw40.00 2.25 Vw 41.93 2.15 Vw 43.80 2.07 Vw 45.27 2.00 Vw 47.05 1.93 Vw48.24 1.89 Vw 50.37 1.81 Vw 51.47 1.77 Vw 52.42 1.74 Vw 55.11 1.67 Vw

TABLE 2 Mean values of d_(hkl) and relative intensities measured on anX-ray diffraction diagram of the calcined IM-18 crystalline solid 2theta (°) d_(hkl) (Å) I/I₀ 7.88 11.21 Vw 8.92 9.91 Vw 10.63 8.31 Vw11.81 7.49 Vw 15.78 5.61 Vs 17.89 4.95 Mw 18.50 4.79 Vw 20.93 4.24 Mw21.68 4.10 Vw 23.26 3.82 W 23.71 3.75 Mw 24.09 3.69 W 25.55 3.48 Vw25.97 3.43 M 26.16 3.40 Vw 26.61 3.35 Vw 26.92 3.31 Mw 29.86 2.99 Vw30.23 2.95 W 31.84 2.81 W 33.73 2.66 Vw 36.18 2.48 Vw 36.66 2.45 Vw37.48 2.40 Vw 39.83 2.26 Vw 42.49 2.13 Vw 44.36 2.04 Vw 45.22 2.00 Vw47.56 1.91 Vw 48.22 1.89 Vw 48.58 1.87 Vw 49.78 1.83 Vw in which: Vs =very strong; S = strong; M = medium; Mw = medium weak; W = weak; Vw =very weak.

The relative intensity I/I₀ is given with respect to a relativeintensity scale where a value of 100 is attributed to the most intensepeak in the X-ray diffraction diagram: Vw<15; 15≦W<30; 30≦Mw<50;50≦M<65; 65≦S<85; Vs≦85.

The IM-18 crystalline solid of the invention has a novel basiccrystalline structure or topology which is characterized by its X-raydiffraction diagram given in FIG. 1 and FIG. 2 respectively.

Said solid IM-18 has a chemical composition defined by the followinggeneral formula: mXO₂:nGeO₂:pZ₂O₃:qR:sF:wH₂O (I), in which R representsone or more organic species, X represents one or more tetravalentelement(s) other than germanium, Z represents at least one trivalentelement and F is fluorine. In formula (I), m, n, p, q, s and wrespectively represent the number of moles of XO₂, GeO₂, Z₂O₃, R, F andH₂O and m is in the range 0.5 to 0.9, n is in the range 0.1 to 0.5, p isin the range 0 to 0.1, q is in the range 0 to 0.2, s is in the range 0to 0.2 and w is in the range 0 to 1.

Advantageously, the molar ratio X/Ge of the framework of the IM-18crystalline solid of the invention is in the range 1 to 10, preferablyin the range 1.5 to 5 and more preferably in the range 2 to 3. The molarratio {(n+m)/p} is 10 or more and is preferably 20 or more. The value ofp is in the range 0 to 0.1, more preferably in the range 0 to 0.05 andeven more preferably in the range 0.005 to 0.02. The value of q is inthe range 0 to 0.2, advantageously in the range 0.02 to 0.2 and moreadvantageously in the range 0.05 to 0.15. According to the invention, sis in the range 0 to 0.2; preferably, s is in the range 0.01 to 0.2; andmore preferably, s is in the range 0.02 to 0.1. In accordance with theinvention, the value taken by w is in the range 0 to 1, preferably inthe range 0.3 to 0.5. In the dried and calcined form of the IM-18crystalline solid of the invention, the values of q, s and w are zero.

In accordance with the invention, X is preferably selected from silicon,tin and titanium; more preferably, X is silicon, and Z is preferablyselected from aluminium, boron, iron, indium and gallium; morepreferably, Z is aluminium. Preferably, X is silicon: thus, the IM-18crystalline solid of the invention, when the element Z is present, is acrystalline metallogermanosilicate with an X-ray diffraction diagramidentical to that described in Table 1 when it is in its as-synthesizedform and identical to that described in Table 2 when it is in itscalcined form. Still more preferably, X is silicon and Z is aluminium:thus, the IM-18 crystalline solid of the invention is a crystallinealuminogermanosilicate with an X-ray diffraction diagram identical tothat described in Table 1 when it is in its as-synthesized form andidentical to that described in Table 2 when it is in its calcined form.

When the IM-18 crystalline solid of the invention is in itsas-synthesized form, i.e. directly derived from synthesis and prior toany calcining and/or ion exchange step which is well known to theskilled, person, said IM-18 solid comprises at least one organicnitrogen-containing species as described below or its decompositionproducts, or its precursors. In the as-synthesized form, the organicspecies R present in the general formula defining the IM-18 solid is(are) at least in part and preferably completely said organic species.In accordance with a preferred embodiment of the invention, R is4-dimethylaminopyridine. Said organic species R, which acts as atemplate, may be eliminated by conventional prior art techniques such asheat and/or chemical treatments.

The IM-18 crystalline solid of the invention is preferably a zeoliticsolid.

The present invention also concerns a process for preparing an IM-18crystalline solid in which an aqueous mixture is reacted which comprisesat least one source of at least one oxide of germanium, at least onesource of at least one oxide XO₂, optionally at least one source of atleast one oxide Z₂O₃, at least one organic species R and at least onesource of fluoride ions, the mixture preferably having the followingmolar composition:

(XO₂+GeO₂)/Z₂O₃:at least 5, preferably at least 10;

H₂O/(XO₂+GeO₂):1 to 50, preferably 3 to 20;

R/(XO₂+GeO₂):0.1 to 3, preferably 0.5 to 1;

XO₂/GeO₂:0.5 to 10, preferably 2 to 10, and highly preferably 3 or 5;

F/(XO₂+GeO₂) :0.1 to 2, preferably 0.2 to 1;

where X is one or more tetravalent element(s) other than germanium,preferably silicon, Z is one or more trivalent element(s) selected fromthe group formed by the following elements: aluminium, iron, boron,indium and gallium, preferably aluminium.

In accordance with the process of the invention, R is an organic speciesacting as an organic template. Preferably, R is the nitrogen-containingcompound 4-dimethylaminopyridine.

The source of element X may be any compound comprising the element X andwhich can liberate that element in aqueous solution in the reactiveform. Advantageously, when the element X is silicon, the source ofsilica may be any one of those currently used in synthesizing zeolites,for example solid powdered silica, silicic acid, colloidal silica,dissolved silica or tetraethoxysilane (TEOS). Of the powdered silicas,it is possible to use precipitated silicas, in particular those obtainedby precipitation from a solution of an alkali metal silicate, such asaerosil silicas, pyrogenic silicas, for example “CAB-O-SIL”, and silicagels. It is possible to use colloidal silicas having different particlesizes, for example with a mean equivalent diameter in the range 10 to 15nm or between 40 and 50 nm, such as those sold under trade names such as“LUDOX”.

The source of germanium may be any compound comprising the elementgermanium and which can liberate that element in aqueous solution in thereactive form. The source of germanium may be a crystalline oxide ofgermanium in any of its quartz or rutile forms. It is also possible touse sources of germanium such as tetraethoxygermanium ortetraisopropoxygermanium. The source of germanium may preferably be anamorphous germanium oxide, GeO₂.

The source of element Z may be any compound comprising the element Zwhich can liberate that element in aqueous solution in the reactiveform. In the preferred case in which Z is aluminium, the source ofalumina is preferably sodium aluminate, or an aluminium salt, forexample the chloride, nitrate, hydroxide or sulphate, an aluminiumalkoxide or alumina proper, preferably in the hydrated or hydratableform, such as colloidal alumina, pseudoboehmite, gamma alumina or alphaor beta trihydrate. It is also possible to use mixtures of the sourcescited above.

The fluorine may be introduced in the form of alkali metal or ammoniumsalts, for example NaF, NH₄F, NH₄HF₂ or in the form of hydrofluoric acidor in the form of hydrolysable compounds which can liberate fluorideanions in water, such as silicon fluoride, SiF₄ or ammoniumfluorosilicate, (NH₄)₂SiF₆ or sodium fluorosilicate, Na₂SiF₆.

In accordance with a preferred implementation of the process of theinvention, an aqueous mixture is reacted which comprises silica,optionally alumina, an oxide of germanium, 4-dimethylaminopyridine and asource of fluoride ions.

The process of the invention consists of preparing an aqueous reactionmixture known as a gel and comprising at least one source of at leastone oxide GeO₂, at least one source of at least one oxide XO₂,optionally at least one source of at least one oxide Z₂O₃, at least onesource of fluoride ions and at least one organic species R. Thequantities of said reagents are adjusted in order to endow that gel witha composition which allows it to crystallize into an IM-18 crystallinesolid with general formula: mXO₂:nGeO2:pZ₂O₃:qR:sF:wH₂O, in which m, n,p, q, s and w satisfy the criteria defined above. Next, the gelundergoes a hydrothermal treatment until the IM-18 crystalline solid isformed. The gel is advantageously subjected to hydrothermal conditionsunder autogenous reaction pressure, optionally by adding gas, forexample nitrogen, at a temperature in the range 120° C. to 200° C.,preferably in the range 140° C. to 180° C., and more preferably in therange 150° C. to 175° C. until solid IM-18 crystals are formed. The timenecessary to obtain crystallization generally varies between 1 hour andseveral months, preferably between 10 hours and 20 days, depending onthe composition of the reagents in the gel, stirring and the reactiontemperature. The reaction is generally carried out with stirring or inthe absence of stirring.

It may be advantageous to add seeds to the reaction mixture to reducethe time necessary for the formation of crystals and/or to reduce thetotal crystallization period. It may also be advantageous to use seedsto encourage the formation of IM-18 crystalline solid, to the detrimentof impurities. Such seeds comprise solid crystals, preferably crystalsof solid IM-18. The crystalline seeds are generally added in aproportion in the range 0.01% to 10% by weight of the mass of oxides(XO₂+GeO₂), XO₂ preferably being silica, used in the reaction mixture.

At the end of the reaction, the solid phase is filtered and washed; itis then ready for the subsequent steps such as drying, dehydration andcalcining and/or ion exchange. For these steps, any of the conventionalmethods known to the skilled person may be employed.

The calcining step is advantageously implemented by means of one or moreheating steps carried out at a temperature in the range 100° C. to 1000°C., for a period in the range from a few hours to several days.Preferably, in order to obtain the calcined form of the IM-18crystalline solid of the invention, the solid in its as-synthesized formis initially heated in a stream of a neutral gas, for example a streamof nitrogen, at a temperature which is preferably in the range 100° C.to 250° C. for a period which is advantageously in the range 2 to 8hours, then calcining in a neutral gas atmosphere, for example in anitrogen atmosphere, at a temperature which is preferably in the range400° C. to 700° C. for a period which is advantageously in the range 6to 10 hours. After these first treatments, the IM-18 crystalline solidobtained is calcined at a temperature which is preferably in the range400° C. to 700° C. for a period which is advantageously in the range 6to 10 hours in a stream of air then for a further period, preferably inthe range 6 to 10 hours, in a stream of oxygen.

The present invention also pertains to the use of said IM-18 crystallinesolid as an adsorbant. Preferably, said IM-18 crystalline solid is freeof organic species, preferably 4-dimethylaminopyridine, when it is usedas an adsorbant. When it is used as an adsorbant, the IM-18 crystallinesolid of the invention is generally dispersed in an inorganic matrixphase which contains channels and cavities which allow the fluid to beseparated to access the crystalline solid. These matrices are preferablymineral oxides, for example silicas, aluminas, silica-aluminas or clays.The matrix generally represents 2% to 25% of the mass of the adsorbantthus formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 & 2 represent diffractograms of crystalline solids of theinvention.

The invention will now be illustrated using the following examples.

EXAMPLE 1 Preparation of a IM-18 Crystalline Solid in Accordance withthe Invention

2.967 g of 4-dimethylaminopyridine (Fluka) was added to 7.67 mL ofdistilled water in a Teflon receptacle with a 20 mL internal volume.1.017 g of germanium oxide (Aldrich) was then added to this solution.The mixture was stirred for 15 minutes using a magnetic stirrer. 8.667mL (8.095 g) of TEOS (tetraethoxysilane, Fluka) was then introduced. Themixture was then stirred for 48 hours at ambient temperature, in orderto evaporate off the ethanol formed by hydrolysis of the TEOS. 1.075 mL(1.215 g) of an aqueous HF solution (40% by weight hydrofluoric acid,Carlo Erba) was then added The mixture was stirred for 15 minutes. Afterweighing and adjusting the quantity of water required, the molarcomposition of the mixture obtained was: 0.8 SiO₂:0.2 GeO₂:0.54-dimethylaminopyridine:0.5 HF:8 H₂O.

The Teflon sleeve containing the synthesis mixture (pH˜9) was thenintroduced into an autoclave, which was placed in an oven at 170° C. fora period of 14 days in the absence of stirring.

After filtering, the product obtained was washed several times withdistilled water. It was then dried at 70° C. for 24 hours. The mass ofthe dry product obtained was approximately 2.29 g.

The dried solid product was initially heated in a stream of nitrogen ata temperature of 200° C. for 4 hours followed by calcining, still in anitrogen atmosphere, at 550° C. for 8 hours. After these firsttreatments, the solid obtained was calcined at 550° C. for 8 hours in astream of air then for a further 8 hours in a stream of oxygen.

The solid obtained was analyzed by X-ray diffraction and identified asbeing constituted by IM-18 crystalline solid: the diffractogram carriedout on the calcined IM-18 solid is shown in FIG. 2.

EXAMPLE 2 Preparation of a IM-18 Crystalline Solid in Accordance withthe Invention

8.477 g of 4-dimethylaminopyridine (Fluka) was added to 6.28 mL ofdistilled water in a Teflon receptacle with a 20 mL internal volume.1.937 g of germanium oxide (Aldrich) was then added to this solution.The mixture was stirred for 15 minutes using a magnetic stirrer. 16.509mL (15.419 g) of TEOS (tetraethoxysilane, Fluka) was then introduced.The mixture was then stirred for 48 hours at ambient temperature, inorder to evaporate off the ethanol formed by hydrolysis of the TEOS.2.047 mL (2.314 g) of an aqueous HF solution (40% by weight hydrofluoricacid, Carlo Erba) was then added The mixture was stirred for 15 minutes.After weighing and adjusting the quantity of water required, the molarcomposition of the mixture obtained was: 0.8 SiO₂:0.2 GeO₂:0.754-dimethylaminopyridine:0.5 HF:3 H₂O.

The Teflon sleeve containing the synthesis mixture (pH˜10) was thenintroduced into an autoclave, which was placed in an oven at 170° C. fora period of 14 days in the absence of stirring.

After filtering, the product obtained was washed several times withdistilled water. It was then dried at 70° C. for 24 hours. The mass ofthe dry product obtained was approximately 3.88 g.

The dried solid product was initially heated in a stream of nitrogen ata temperature of 200° C. for 4 hours followed by calcining, still in anitrogen atmosphere, at 550° C. for 8 hours. After these firsttreatments, the solid obtained was calcined at 550° C. for 8 hours in astream of air then for a further 8 hours in a stream of oxygen.

The solid obtained was analyzed by X-ray diffraction and identified asbeing constituted by IM-18 crystalline solid: the diffractogram carriedout on the calcined IM-18 solid is shown in FIG. 2.

EXAMPLE 3 Preparation of a IM-18 Crystalline Solid in Accordance withthe Invention

2.967 g of 4-dimethylaminopyridine (Fluka) was added to 7.62 mL ofdistilled water in a Teflon receptacle with a 20 mL internal volume.0.152 g of aluminium hydroxide (63% to 67% by weight of Al₂O₃, Fluka)and 1.017 g of germanium oxide (Aldrich) were then added to thissolution. The mixture was stirred for 1 hour using a magnetic stirrer.Approximately 0.070 g of the product from the synthesis described inExample 1 which had been ground (i.e. 2% of the weight of the oxidesSiO₂, GeO₂ and Al₂O₃) were then introduced as seeds, and the mixture wasstirred for 15 minutes. 8.667 mL (8.095 g) of TEOS (tetraethoxysilane,Fluka) was then introduced. The mixture was then stirred for 48 hours atambient temperature, in order to evaporate off the ethanol formed byhydrolysis of the TEOS. 1.075 mL (1.215 g) of an aqueous HF solution(40% by weight hydrofluoric acid, Carlo Erba) was then added and themixture was stirred for 15 minutes. After weighing and adjusting thequantity of water required, the molar composition of the mixtureobtained was: 0.8 SiO₂:0.2 GeO₂:0.02 Al₂O₃:0.5 4-dimethylaminopyridine:0.5 HF:8 H₂O (+2% by weight with respect to the oxides of the seeds).

The Teflon sleeve containing the synthesis mixture (pH˜9) was thenintroduced into an autoclave, which was placed in an oven at 170° C. fora period of 14 days in the absence of stirring.

After filtering, the product obtained was washed several times withdistilled water. It was then dried at 70° C. for 24 hours. The mass ofthe dry product obtained was approximately 1.98 g.

The dried solid product was initially heated in a stream of nitrogen ata temperature of 200° C. for 4 hours followed by calcining, still in anitrogen atmosphere, at 550° C. for 8 hours. After these firsttreatments, the solid obtained was calcined at 550° C. for 8 hours in astream of air then for a further 8 hours in a stream of oxygen.

The solid obtained was analyzed by X-ray diffraction and identified asbeing constituted by IM-18 crystalline solid: the diffractogram carriedout on the calcined IM-18 solid is shown in FIG. 2.

EXAMPLE 4 Preparation of an Adsorbant Containing the IM-18 CrystallineSolid

The solid used was the calcined solid of Example 2.

It was formed into extrudates by mixing with boehmite (Pural SB3, Sasol)in a Z arm mixer and extruding the paste obtained using a plug extruder.The extrudates were then dried at 120° C. for 12 h in air and calcinedat 550° C. for 2 hours in a stream of air in a muffle furnace.

The prepared adsorbant was composed of 80% by weight of zeolitic IM-18solid and 20% by weight of alumina.

1. An IM-18 crystalline solid in its calcined form having an X-raydiffraction diagram including at least the peaks shown in the tablebelow: 2 theta (°) d_(hkl) (Å) I/I₀ 7.88 11.21 Vw 8.92 9.91 Vw 10.638.31 Vw 11.81 7.49 Vw 15.78 5.61 Vs 17.89 4.95 Mw 18.50 4.79 Vw 20.934.24 Mw 21.68 4.10 Vw 23.26 3.82 W 23.71 3.75 Mw 24.09 3.69 W 25.55 3.48Vw 25.97 3.43 M 26.16 3.40 Vw 26.61 3.35 Vw 26.92 3.31 Mw 29.86 2.99 Vw30.23 2.95 W 31.84 2.81 W 33.73 2.66 Vw 36.18 2.48 Vw 36.66 2.45 Vw37.48 2.40 Vw 39.83 2.26 Vw 42.49 2.13 Vw 44.36 2.04 Vw 45.22 2.00 Vw47.56 1.91 Vw 48.22 1.89 Vw 48.58 1.87 Vw 49.78 1.83 Vw

in which: Vs=very strong; S=strong; M=medium; Mw=medium weak; W=weak;Vw=very weak, and having a chemical composition expressed by thefollowing general formula: mXO₂:nGeO₂:pZ₂O₃:qR:sF:wH₂O, in which Rrepresents one or more organic species, X represents one or moretetravalent element(s) other than germanium, Z represents at least onetrivalent element and F is fluorine, m, n, p, q, s and w respectivelyrepresenting the number of moles of XO₂, GeO₂, Z₂O₃, R, F and H₂O and mis in the range 0.5 to 0.9, n is in the range 0.1 to 0.5, p is in therange 0 to 0.1, q is in the range 0 to 0.2, s is in the range 0 to 0.2and w is in the range 0 to
 1. 2. An IM-18 crystalline solid according toclaim 1, in which X is silicon,
 3. An IM-18 crystalline solid accordingto claim 1, in which Z is aluminium.
 4. An IM-18 crystalline solidaccording to claim 1, in which the molar ratio {(n+m)/p} is 10 or more,p is in the range 0.005 to 0.02, q is in the range 0 to 0.2, s is in therange 0 to 0.2 and w is in the range 0 to
 1. 5. A process for preparingan IM-18 crystalline solid according to claim 1, consisting of mixing,in an aqueous medium, at least one source of at least one oxide GeO₂, atleast one source of at least one oxide XO₂, optionally at least onesource of at least one oxide Z₂O₃, at least one source of fluoride ions,and at least one organic species R, then carrying out hydrothermaltreatment of said mixture until said IM-18 crystalline solid is formed.6. A process for preparing an IM-18 crystalline solid according to claim5, in which the molar composition of the reaction mixture is such that:(XO₂+GeO₂)/Z₂O₃:at least 5; H₂O(XO₂+GeO₂):1 to 50; R/(XO₂+GeO₂):0.1 to3; XO₂/GeO₂:0.5 to 10; F/(XO₂+GeO₂):0.1 to
 2. 7. A preparation processaccording to claim 5, in which said organic species R is4-dimethylaminopyridine.
 8. A preparation process according to claim 5,in which the reaction mixture is supplemented with seeds.
 9. (canceled)10. A process for separating a fluid, comprising contacting said fluidwith an adsorbent containing an IM-18 crystalline solid according toclaim 1.